Depends. If you're talking about a free online test I can take to prove I have basic critical thinking skills, maybe, but that's still a slippery slope. As a legal adult with the right to consent to all sorts of things, I shouldn't have to prove my competence to someone else's satisfaction before I'm allowed autonomy to make my own personal decisions.

If what you're suggesting is a license that would cost money and/or a non-trivial amount of time to obtain, it's a nonstarter. That's how you create an unregulated black market and cause more harm than leaving the situation alone would have. See: the wars on drugs, prostitutes, and alcohol.